The Real Reason Why
by SPN221B
Summary: Ever wondered what prompted Tadashi to make Baymax? Could it have been Hiro's fault all along? Could it have been that Tadashi knew he couldn't always be there to protect his brother? Well, let's find out! First Big Hero 6 story! Enjoy! Lots of brotherly fluff, cause that's who I am!
1. Chapter 1

**Hello, this is PFT3000. I am new to this fandom, but have wrote 40 other stories, so this is my 41st! So this was just going to be a one-shot, but I kinda liked where I was going with this so it ended up being three chapters** **. This is set about two years before the movie, so enjoy!**

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 _Chapter one, Tadashi's P.O.V._

It had been a completely exhausting day. I had one goal on my mind and that was sleep. Aunt Cas understood. She always did. I climbed the stairs, completely oblivious to the rest of the world. I dropped my backpack, and flopped down on the bed. I was almost asleep when I heard Hiro come in.

"Tadashi? You awake?" he asked, in a quiet, quivering voice.

i sat up on my elbows, yawning, and looked questioning at the boy whose hoody was pulled over his face. "I am now. What's up?"

Hiro didn't say a word, instead just turned and walked away. I jumped off the bed, acidently pulling back the hood on Hiro's hoody, and gasped at the sight of his face. My brother had a bloody lip, a black eye, and his face was covered in bruises. My eyes flared in anger at this.

"Hiro, who did this?" I asked, turning him by his shoulders.

He wiped away a few tears, and merely mumbled. "It's nothing. I'm fine Tadashi."

"No, you're not fine. I want to hear how this happened. No one is even allowed to touch my brother except for me."

A smile escaped, but quickly dissaperence. "Why would you even care? It's not like you noticed before." he whispered, sliding down the edge of the bed, ending up on the floor, and I promply followed him.

"This has happened before?" I raised my eyebrow.

My little brother nodded and started crying softly. I pulled him into a hug, comforting him while he cried. I stroked his hair back and he leaned further into me. I didn't mind at all, and just let him be.

Surprisingly, Hiro was quick to fall asleep in my arms. I frowned looking at his bruises and cuts. My frown became even deeper as I thought back to what he said. This had happened before? Why had he never told me? I could've prevented it from happening again.

I laid Hiro gently on my bed and went to get a wet rag. Cleaning up my brother, I sighed when he flinched at the touch. If I ever found out who had done this, they would not live to see another day. I smoothed his hair again, smiling slightly when he settled in a calm, almost peaceful sleep. Pulling the covers over my brother, I joined him in his slumber.

* * *

My eyes popped open. Something wasn't quite right. I glanced at the clock, it was only 11:42. I hear a noise and reliazed that it's Hiro talking to me. Listening closer, I hear he's not exactly talking as much as he's having a nightmare. I frowned in worry, but couldn't do anything for him. It was uncommon for Hiro to have nightmares, but not impossible.

Hiro started to toss and turn, but countinued to sleep. I watched for a few minutes, and started to drift back off. I was almost there, when Hiro started yelling and kicking. I grabbed his shoulders, trying to wake him, but it just made it worse. Instead, I started whispering soft words, trying to comfort him.

"No! Tadashi! Don't! I'm sorry! Tadashi don't leave me! Please dont! I'm sorry. Tadashi. No." Hiro's yells, soon became cries of fear and sadness.

i watched with sad eyes, not even wanting to know what was going through my brother's head right now. He suddenly shot up and yelled my name, crying with every word he spoke.

"Tadashi! I'm sorry! Please don't leave me!" he cried out the words.

i hugged him as tight as I possibly could. "Hey there. Don't cry. I'm right here. I'll never leave you."

It was pretty clear Hiro wasn't fully awake. He was drifting in and out of reality. He kept crying, making me extremely worried. My little brother rarely cried this hard. And I never knew what to do when he did.

"Hiro," I said his name, trying to bring him to his senses. "I'm right here. I'd never leave you. I love you to much."

"But you said you hated me, and never wanted to see me again. And then you left me in the dark. And they hurt me. I called out for you to help, but you just kept walking. I'm sorry! I didn't mean to make you mad." he sobbed, shoving his face into my shirt, as it became soaked with tears.

"What! Hiro, I would never hate you. And I've never leave you in trouble. You're my brother. I could never hate you."

The boy just kept crying, truely upset. After a while his sobs that had been racking his body, turned to much less violent cries. Looking up at me, eyes red and lip quivering, he took a deep breath.

"Can I spend the rest of the night with you?" he asked, and I heard the silent begging note in his voice.

I nodded. "Of course. I would never turn you away."

We both climbed under the covers and slowly drifted asleep. Hiro moved closer to me, and I embraced it, happy to know my brother was safe. And in the end, we both slept slightly better that night.

* * *

The next morning was intresting, to say the least. It was Saturday so that meant we could sleep in until 9:30. But one look at Hiro, and you knew he wasn't going anywhere. He out like a rock. I woke up thirty minutes before the dead line. I got dressed and rushed downstairs to help Aunt Cas with the morning rush.

"Morning Tadashi. How did you sleep?" Aunt Cas asked.

I smiled. "Great for the most part. Can't say the same for Hiro though."

Aunt Cas stopped what she was doing to look at me closely. "Okay, out with it. What happened?"

"He had a really bad nightmare. It was really hard on him Aunt Cas. I was up with him for some time." I hated lying, but thinking twice about it, I wasn't really lying, just not telling the full story.

She sighed sadly. "Is he okay?" she questioned.

I nodded. "He'll be fine. We should just let him sleep in some."

We then procceded to hear a loud crash upstairs. Aunt Cas and I looked at each other with wide eyes. I then turned and raced through the cafe, and up the stairs. Stopping at the top, I heard soft crying.

"Hiro? Is everything okay up here?" I asked gently.

His voice quavered as he spoke. "Tadashi? Where are you? Where am I?"

I rushed over and waved my hand in front of his face. His eyes were wide open and he kept blinking, but something just wasn't right. It was as if they were missing a component of some sort.

"Hiro, how many fingers am I holding up?" I asked the simple question.

He shook his head, clearly frustrated. "I don't know Tadashi! I can't see you. I can't see anything. It's all dark!" he shouted.

I took his hands in mine. "It's alright Hiro. I'm right here. I have you."

Once he calmed down, I looked back into his eyes. Instead of their normal chocolate brown they were now pure black. His pupils were almost nonexistent. Hiro needed to see an eye doctor now.

"Hiro, I need you to listen to me and answer a few questions. For one, close your eyes. Two, do your eyes hurt?"

"They do, but it's even worse when they're open." he answered.

"Okay," I started again. "One last question. Who beat you up yesterday? I need to know."

This time, Hiro hesitated. "It was, um, Blake McCallum. But why does that even matter?"

"I just needed to know. Now listen, I'm going downstairs to get Aunt Cas. I promise, I will come back for you. Just don't panic, okay?" I reinsured him.

"Okay. Tadashi?" his voice was shaking again.

I turned to look at him. "Yes Hiro?"

"You really will come back? You won't leave me alone?"

"Hiro," I started, wrapping my arms around him. "I'll always come back. I would never leave my brother. For as long as I live, I will always be here for you, no matter what."

He nodded and snuggled closer. I sat there, my brother in my arms, thinking of what needed to be done. Releasing Hiro, I got up and walked towards the stairs. looking back back towards my brother, who was resting his head on his knees. I nodded. He would be fine here for a little while.

Rushing back downstairs, I bump into Honey Lemon. I tried to continue on, but she stopped me. I silently cursed myself for having such persistent friends.

"Tadashi? What's wrong?" she asked.

Scanning the room, I see Aunt Cas at a table with all my other friends, serving drinks. I weave my way through the cafe, my heart pumping twice as fast as normal.

"Sorry Honey. Can't talk right now."

Making my way through the crowded cafe, I finally get to Aunt Cas. "Aunt Cas, Hiro's sick." I say in a lowered voice.

"How bad is it? Does he need to go to the doctors?" she asked, countinuing her work.

"He can't see anything. He's completely blind." it hurt me to say it, but it was the truth, and right now, Aunt Cas needed to know.

She dropped the plates that were in her hands and they shattered. She didn't move to do anything about them, and instead grabbed her megaphone that she used when she had to close down early. I know she hated closing early, but Hiro was more important than her work right now.

"Attention dinners!" she began. "There has been a small emergency and I am forced to shut down early. Consider all unpaid food on me. Thank you!"

Everyone shuffled out of the cafe and I finished cleaning up the broken plates. As I dumped them in the trash can, Aunt Cas raced up to me.

"Go get Hiro, and put him and yourself in the truck. I'll be out there in a minute." she told me and then ran off.

I went to get Hiro and was surprised to find him in the exact place I left him.

"Tadashi? Is that you?" he asked in an extremely weak voice.

"Yes, it's me. Aunt Cas told me to come and get you. We're going to take you to an eye doctor. Can you walk?"

Hiro nodded and got up. He took three steps before falling backwards, barley missing the corner of the table before I caught him. From the pain I saw in each step, I was sure that he had muscle fatigue. Tears sprang to his eyes, as he admitted the inevitable.

"I, I can't Tadashi. I'm sorry." he looked down in shame.

"Hey there. There's nothing to be ashamed of. All that matters is that we find out what's wrong and fix it."

And with that, for the next six days, we only wished we had more time together. Because Hiro and I were in for the shock of a lifetime. I only wish I had been there more for little brother.

And he did too.

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 **So there's chapter one! I hoped you enjoyed it, and please! Review!**

 **Best Regards,**

 **PFT3000**


	2. Chapter 2

**Hey everyone! Thank you sooo much for all of the reviews! I think I got six, and I was expecting, maybe two, so thank you very much! Well here's the next chapter! Enjoy!**

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Hiro was quickly taken into an examination room, but only his legal guardian was allowed to be with him. We both put up an exhausting fight, Hiro not wanting to leave my side, and I didn't want some stranger, a doctor or not, just taking my brother. But not twenty minutes later, I came to my senses.

"Hiro, I don't want to leave you either. I don't want you to leave me. But the sooner we get this over with, the sooner we'll be back together." I reasoned. "I promise you with my life, I will be right here."

I had whispered the last part in his ear, no one else knowing. They led him into the room, and slammed the door, while I chewed my lip. Now three hours later, I was pacing the room. I had heard nothing from Aunt Cas or the doctor. This really sucked. I was out here, while everyone else was with MY brother!

"Tadashi Hamada? You can come in now." a nurse peeked out the door.

I pushed past her, not even caring about manners. Hiro was lying on one those hospital beds, sleeping soundly for the moment. Aunt Cas was crying as the doctor talked to her. Seeing me, she motioned for me to come over. I looked worridly from her to Hiro, trying to decide which to go to. Finally, I walked towards Aunt Cas.

"What's wrong with Hiro? Why can't he see?" I asked bluntly.

"Your brother is suffering from a disease known as Laracose. Some of the sideaffects are muscle fatigue, headaches, loss of sight, nausea, and some other things, such as internal bleeding. As Hiro's brother, I was wondering if you had seen any of these signs other than blindeness." the doctor asked.

But I couldn't answer. Hiro had Laracose? I was no medical expert, but I did know the survival rate of this was fourteen out of one hundred. And those who were able to see again was a three out of the fourteen. Those weren't great chances at all. There had to be some way...

"Tadashi? Did you hear me?" the doctor cut off my thoughts.

I nodded. "There's been no headaches or nausea that I know of. But he couldn't walk so that could be a sign of muscle fatigue. Will he be alright?"

The doctor's eyes grew slightly hopeful. "Then he still has a chance. We need to get Hiro into an operating room now, and progress from there. If Hiro is alright with doing this of course." he looked towards the sleeping boy.

Hiro was still out like a light, and I went and sat next to him. When he woke up, I was the only other one in the room. I tapped his shoulder, and he slightly freaked out.

"Who was that?!" he asked.

"It's just me. Tadashi."

He took a deep breath of relief. "You kept your promise."

"Well," I started. "Of course I did. I would never break one I made to you."

Hiro smiled at that. We both sat in silence for a while until my brother asked the question that was nagging at the back of everyone's mind. No one had been brave enough to say it aloud until now though.

"Tadashi? Am I going to die?" his words filled with great sadness.

"I, I don't know. You have Laracose. It's an extremely rare chance you'll survive and even rarer that you'll get your sight back." I answered as honestly as I could. "I'm sorry."

He merely shrugged. "Oh. Well I guess this could be goodbye?"

I nodded, feeling the hot tears in my eyes. "As much as I hate to say it, yes, it could be."

"Okay... I'll miss you Tadashi, but I guess this is for the best..."

"I'll miss you too Hiro. No one could ever come close to replacing my little brother." I swiped angrily at my tears.

"I know... Tadashi. Thank you." he said weakly.

"For what? I've done nothing to help."

"For, for," he stuttered. "For being the best brother in the whole world."

We were silent and motionless again until Hiro threw his arms around me. I was taken aback for a second, but then hugged him back. I let go, and he sniffed.

"Do you have to go?" he asked sadly.

I nodded. "I do. But I'll be back as soon as you come out. Now go get better. And don't die on me. I couldn't bare to live without you."

"Mr. Hamada? We need to ask you to leave now." another nurse said.

I squeezed Hiro's hand, and did a small fist bump, getting him to smile. I watched them take my brother, only Aunt Cas being allowed in again. I sat down on a chair, and took a deep breath, fighting the tears that were threatening to fall. My lip trembled, and I smiled when I saw Honey Lemon, Wasabi, Fred, and GoGo. None of them had never ever met Hiro, yet they were all here.

I waved them over, taking another deep breath. I explained what was going on, glad to have at least my friends close. They all stayed for hours and by the time they left it was past seven. I was offered a plate of food from the cafeteria by one of the workers, but I refused. I wasn't, couldn't, eat anything until I knew my brother was going to be okay.

I fell asleep, deeply unaware of what was happening for a good two hours, until my phone went off. I awoke with a start, startled by my phone's ringtone after all that happened these past two days. I had been recording Hiro one day work on his invention for the school science fair, when something went wrong. He had started to run, and yell at me to get out too. I, meanwhile, had stood there laughing my head off, not seeing the big deal. That was until a piece of flying debri hit me in the head, giving me a concussion.

My ringtone was set as that because I was always extremly alert whenever Hiro was in trouble. But after everything, I may have to change it for a little while.

"Run Tadashi! Run! Tadashi, No!" the ringtone sounded again.

I picked it up, and answered when I saw it was Aunt Cas. "Hello? What's up Aunt Cas?"

"We need you back here. Hiro refuses to let us do this without you." she responded.

"Be there in a minute." I ended the call, already running towards where my brother was.

By the end, eleven nurses and two doctors were chasing me. I slowed as I got closer and walked in like I didn't have thirteen people on my tail. I saw Hiro fighting everyone in the room, including Aunt Cas. I walked towards him, and started to whisper into his ear.

"Hiro. It's me again. Tadashi. Stop fighting. I've got your back. No one will get past me. I know you can't see and it's really freaking you out, but no one is trying to hurt you. They all want to help you, that's all. Just let them do this." I whispered, hoping to calm and reinsure him.

I then heard the two words I never thought I'd hear Hiro say aloud. "I'm scared Tadashi. This is all just to confusing. I don't think I can do it." he whispered back, hurt clear in his voice.

I merely smiled. "I know you can do it. You're the strongest person I know. I have no doudt about it. You'll make it. You just have to believe in yourself."

We hugged and Hiro let the doctors do what they needed to. Aunt Cas collapsed in my arms, crying for Hiro. And I silently cursed myself for being the oldest sibling. Why? Because I wanted to cry too, but if I did that, no body would be able to hold it together.

And we couldn't possibly have that, now could we?

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 **And cut! Only one chapter left, and I hope to have out sooner than I did this one. And if someone reading this is medically trained, please know when I made up the disease Laracose, that I was thinking, "Fictional world, fictional disease." Well I hope you all enjoyed, and please review!**

 **Best Regards,**

 **PFT3000**


	3. Chapter 3

**Like I said, I wanted to have this one out sooner than the last chapter, and I did! Its been what, a day? Well I hope you enjoy this last chapter, but two one-shot pieces will be coming out for this soon! The first will be called Hidden Video. Well enjoy!**

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I haven't seen Hiro or Aunt Cas since Saturday. That was four days ago. Four days! I was tired, hungry, impatient, and restless. Unless he wasn't allowed visitors during recovery, no surgery should take this long. That or they were delaying the one thing I had always feared.

I was mentally thinking if I should leave or not. I was missing my courses, and the cafe needed to open again. But I had promised Hiro I would be here. If he came out of surgery and awoke while I wasn't here, he'd panic. But if I missed much more of this class, it wouldn't be worth going anymore. And with the cafe closed, Aunt Cas could go out of business, but Hiro was my brother. What had the Hamada brothers done to deserve all of this?!

"Tadashi Hamada? You're brother is awake now." a nurse said, and I barged right past.

When I first walked in that door the first thing I noticed was that Aunt Cas was in a dead sleep. Hiro was awake though and his eyes had turned back to their normal chocolate brown. I put my hands in my pockets, crossing my fingers, hoping, praying, that my little brother could see again.

"Hiro?" I said, my voice shaking.

His head snapped towards me. "Tadashi?"

"Can, can you see me?" I stumbled over the words.

"I," he started. "I can. I can see everything. It's a little blurry, but it gets clearer as it gets closer."

I hugged Hiro as tight as I could, glad that he could see, that he was going to be alright. So I let the tears fall, finally able to let out all of the emotions I had kept hidden for six days. Hiro, completely shocked that I, of all people, was crying, just hugged me back. I gave him a big smile.

"Let's go home."

I put the last piece in place, and stood back to admire my work. Wiping my hands together, I took a deep breath. After everything That had happened recently, Hiro getting sick, beat up, and almost dying, I had chosen a new robotics project, putting the other aside for later. If it worked like I hoped, it would keep Hiro safe even when I wasn't around.

I grabbed the director's board, and started the video. "I'm Tadashi Hamada, and this is the first test of my robotics project."

"Hello. I am Baymax, your personal healthca... it started a loud shrieking noise.

"Stop, stop, stop!" I scrambled to shut it off.

I collapsed in a chair, taking off my hat and running my fingers through my hair. I had a long way to go, but one day Baymax would help a lot of people.

And my brother was the real reason why.

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 **And we're done! Hope you all enjoyed, and see you soon! As I said, there will be companion one-shots, but first I'm going to post a totally, non-related one shot called Red and Blue. Well please review!**

 **Best Regards,**

 **PFT3000**


	4. Offer

Hey everyone! In the spirit of Christmas I have an offer for you! For every review you leave on one of my stories, I'll review one of yours! I'll do this until January 1st, 2017 starting today, December 22nd. Happy Holidays, Merry Christmas, Happy Hannaka, and Happy New Years(unless you're in China of course).

Best Regards,

PFT3000


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